From: Peter Maydell <peter.maydell@linaro.org>
To: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: "Laurent Vivier" <laurent@vivier.eu>,
"Eduardo Habkost" <eduardo@habkost.net>,
"Marcel Apfelbaum" <marcel.apfelbaum@gmail.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Yanan Wang" <wangyanan55@huawei.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"David Hildenbrand" <david@redhat.com>,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org,
"Christian Borntraeger" <borntraeger@linux.ibm.com>
Subject: Re: [PATCH 1/2] linux-user: Fix siginfo_t contents when jumping to non-readable pages
Date: Fri, 5 Aug 2022 09:50:54 +0100 [thread overview]
Message-ID: <CAFEAcA9FG+b4=-QNujG5Prx_me8uw7YTWjk-mqr3_X1Wb0wHzg@mail.gmail.com> (raw)
In-Reply-To: <20220804182359.830058-2-iii@linux.ibm.com>
On Thu, 4 Aug 2022 at 19:50, Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> When the first instruction of a translation block is located in a
> non-readable page, qemu-user fills siginfo_t correctly. For the other
> instructions the result is as if it were the first instruction, which
> is not correct.
>
> The reason is that the current logic expects translate_insn() hook to
> stop at the page boundary. This way only the first instruction can
> cause a SEGV. However, this is quite difficult to properly implement
> when the problematic instruction crosses a page boundary, and indeed
> the actual implementations do not do this. Note that this can also
> break self-modifying code detection when only bytes on the second page
> are modified, but this is outside of the scope of this patch.
Which guests do you observe this on ? I think we should indeed
fix this in the translators. More specifically, I think we should
get this correct already on Arm, and I would expect it to work
correctly on all the fixed-insn-width architectures, which can't
have page-crossing-insns to start with. x86 probably gets this wrong.
thanks
-- PMM
next prev parent reply other threads:[~2022-08-05 8:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-04 18:23 [PATCH 0/2] linux-user: Fix siginfo_t contents when jumping to non-readable pages Ilya Leoshkevich
2022-08-04 18:23 ` [PATCH 1/2] " Ilya Leoshkevich
2022-08-05 8:50 ` Peter Maydell [this message]
2022-08-05 10:28 ` Ilya Leoshkevich
2022-08-05 10:55 ` Peter Maydell
2022-08-04 18:23 ` [PATCH 2/2] tests/tcg: Test " Ilya Leoshkevich
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